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Appendix VL

P. 568. Ball Bearings.—Fig. 987 shews a recent form of
ball-bearing cage having some interesting features. The balls are
made of hard tool steel, and are sprung between the two rings

A and B, also of tempered steel, the latter having concave grooves
to receive them. The rings are then forced into place, B upon
the shaft c and A within the bearing or wheel D. The system is
being applied pretty extensively in motor-car practice.

J P. 569. Friction Clutches.—The design of a friction
clutch will depend very much upon the use to which the clutch
is to be put. Thus Fig. 589 is a case where slipping only is to
be provided for, and Fig. 588 is meant only for disengaging.
Nowadays, as for motor-cars, clutches are required that will not
only engage and disengage without shock, but will also slip to
any desired extent within the limits of tight and free, and thus
supply a very perfect variable speed gear. A combined slipping
and disengaging clutch should be free from any tendency to
stick, the wear should not be considerable, and the frictional heat
should be constantly and automatically removed. r The Bagshaw
clutch, Fig. 988, is very simple, and is a disengaging clutch only.
One shaft A is provided with a drum B/in which is a split ring J
running freely within it when out of gear. The other shaft c
carries a disc r>, through which passes the wedge F. When the
wedge is moved leftward by the lever boss B it separates the two
levers GO, that in ten expand the ring j at the point H, and
thus cause die gripping connection between the shafts. The